Basal and therapy-driven hypoxia-inducible factor-1α confers resistance to endocrine therapy in estrogen receptor-positive breast cancer
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Xiaoqing Jia1,*, Qi Hong1,*, Li Lei2,*, Daqiang Li1, Jianwei Li1, Miao Mo3, Yujie Wang1, Zhimin Shao1, Zhenzhou Shen1, Jingyi Cheng4, Guangyu Liu1
1Department of Breast Surgery, Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China
2Department of Breast Surgery, The First People's Hospital of Kunming, Kunming, P.R. China
3Clinical Statistics Center, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China
4Department of Nuclear Medicine, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University Shanghai, P.R. China
*These authors have contributed equally to this work
Guangyu Liu, e-mail: email@example.com
Jingyi Cheng, e-mail: firstname.lastname@example.org
Keywords: HIF-1a, endocrine resistance, zoledronic acid, estrogen receptor, breast cancer
Received: December 14, 2014 Accepted: January 31, 2015 Published: April 13, 2015
Resistance is an obstacle to endocrine therapy for breast cancer. We measured levels of hypoxia-inducible factor (HIF)-1α in 52 primary breast cancer patients before and after receiving neoadjuvant endocrine therapy with letrozole for at least 3 months. Pre-treatment levels of HIF-1α were associated with negative clinical outcome. Furthermore, levels of HIF-1α were increased in post-treatment residual tumors compared with those in pre-treatment biopsy samples. In animal studies, xenografts stably expressing HIF-1α were resistant to endocrine therapy with fulvestrant compared with the effects in control xenografts. Additionally, HIF-1α transcription was inhibited by zoledronic acid, a conventional drug for the treatment of postmenopausal osteoporosis, and was accompanied by a marked inhibition of the RAS/MAPK/ERK1/2 pathway. HIF-1α is a determinant of resistance to endocrine therapy and should be considered as a potential therapeutic target for overcoming endocrine resistance in estrogen receptor (ER)-positive breast cancer. In addition, zoledronic acid may overcome endocrine resistance in ER-positive human breast cancer by targeting HIF-1α transcription through inhibition of the RAS/MAPK/ERK1/2 pathway. Clinical studies on the administration of zoledronic acid as a second line treatment in patients who failed endocrine therapy should be considered to improve therapeutic outcomes in breast cancer patients.
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